It is well known to employ a splicing process for the purpose of joining together two yarn ends which are formed during the processing of yarns, for example, during spooling or winding. The actual splicing process is preceded by a preparation process in which the filaments of the yarn ends are disengaged and separated from one another. In two known methods for splicing yarn ends, shown in German OS No. 2,945,504 and OS No. 2,939,481, the preparation process for the yarn ends is carried out by air jet nozzles. In these nozzles, a twisting motion is imparted to the yarn ends by various means such as, for example, transverse holes.
It must be ensured that the direction imparted is opposite to the yarn twisting direction so that the yarn end is separated by untwisting, but this also involves a risk of overtwisting, either in the reverse direction or, if the air direction is incorrect, overtwisting without accomplishing any untwisting. If yarns having a S-twist are replaced by yarns having a Z-twist while using one of these methods, it is necessary during this changeover to also reverse the direction of the angular momentum of the air imparted by the air jets. Apart from this disadvantage, there is the further problem that these methods are not suitable for yarns not having a well-defined twist such as, for example, twines or open-ended yarns.